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I got an answer from reddit.
"Because you're mining on a variable difficulty pool... Which means you start out mining super low diff, and then it auto adjusts to a different difficulty level so that you get X amount of shares per X amount of time.
And now for the obligatory mention of NO, if you restart the miner a million times you aren't making $$$$$$$$$$$. Low diff shares worth less than high diff ones." - CrateMayne
Welcome to Bitcoin.SE! Your question is very vague and too broad and will be closed as such. If you can edit your question with more specific information, then the question may be reopened. Please edit your question to include what software you are using and the mining pool you are mining with. – Andrew Chow – 2017-12-19T04:03:45.923